Hydraulic Fracturing Behavior in Shale with Water and Supercritical CO₂ under Triaxial Compression

Table 3

Comparison of shale breakdown pressure variation.

No.	Bedding plane angle	Fracturing fluid	Injection rate (ml/s)	Breakdown pressure (MPa)	Reduction proportion; ()
W12	0°	Water	0.2	54.56	28%
W18	90°			39.14
S12	0°	SC-CO2		40.51	23%
S18	90°			31.09
W1	0°	Water	0.3	70.37	40%
W7	90°			42.45
S1	0°	SC-CO2		52.15	27%
S7	90°			38.04

denotes the breakdown pressure of shale with a bedding plane angle of 0°. denotes the breakdown pressure of shale with a bedding plane angle of 90°.